The figure shows the median titres for three serogroups in men and women, depicted as a boxplot. The upper and lower limit of the box represents the first and third quartile. The cross represents the median of the group. The upper and lower limit of the range is presented as horizontal bars on a vertical axis. The large range between upper and lower limits are mostly caused by single samples that might be considered outliers. The distribution of the titres is best represented by the medians, and the first and third quartile limits.